1.) Spike the punch. 750 mL of Everclear for every 5 gallons should be fair.
Right, official college party, probably not a good idea.
Thriller/Michael Jackson is always on the table.
Bloody something or another, copious amounts of fake blood everywhere. Fake blood water balloon fight? Brain-shaped foods everywhere.
What really goes on in FEMA death camps (lulz, works better if your playerbase is informed enough not to believe in those)?
An X-Files episode.
Then again I don't know shit about hosting parties for sober people. The formula is pretty much: Happy dance music transitioning into dirty rap with some (sadly) ironic rock songs thrown in between so hipsters and women have time to take retarded pictures of themselves for Facebook that they'll later try to bury/untag between awkward, mass-participatory hooch-fueled grinding episodes.
Lighting (low, ambient; dark but not rape-y) is key, a fog machine would be super, and bubble machines are also badass and give ADD people a way to interact, which describes/serves a huge sector of the HvZ demographic.
Musically, if you're going with a Zombie Prom, you gotta have some "conventionally dark" shit in there. White/Rob Zombie, Marilyn Manson (composed several awesome tracks on the Resident Evil [Movie] Soundtrack for reference, which Savage sampled in Swing and Lil' Wyte sampled heavily in Oxy Cotton), ya know, spooky stuff. But not too spooky like Lustmord. Unless you're going for that, in which case I applaud your balls/ovaries and taste. There's also a few 'classic' Zombie-themed songs that should be in there (probably) that I hate and won't name (you can't dance to any of them, anyway). You can hire a DJ, but they're expensive and now that everyone has laptops, overrated.
Drinks and food wise, keep those in a relatively well lit area because people have an aversion to eating/drinking what they can't see. Bulk 2 Liters of common sodas and plastic/paper cups with bags of ice can keep most people happy if it is determined that a punch bowl is too much of a potential hazard (probably is more trouble than worth). Sugary foods are best. No Twinkies, sadly. No one ever seems to agree on meats (meatballs v lil smokies v sliced salami) but cheddar and crackers is universally appreciated. Having water available might be good as well, since people overdo it at times and all it takes is one neckbeard sans inhaler to trigger a trip to the medic, as we've seen countless times in HvZ.